Asuna ALO costume is different with Aincrad arc. In ALO or Alfheim Online, Asuna is wearing the blue costume, same with her blue-haired. But her fight style is still same, she’s using speed ability as a healer, so people always calling her as berserk healer. The costume is also favorited by cosplayers.
But, if you still love Asuna costume from Aincrad arc, you can still find it in Anime Bibly. The site is selling that stuff with the cheap price, but the quality of costume is superb. You can also find another Asuna costume in that marketplace, including the ALO version.